Position locationing capabilities have become increasingly important to various industry sectors as they look for ways to offer new revenue-generating products and services to their customers. Location-based applications encompass a broad range of markets, including, telecommunications, healthcare, fleet management, and security applications. In all cases, providing the accurate position location services under all circumstances is the predominant requirement.
Location information can be retrieved by various existing infrastructures and technologies. The most popular position location system is the Global Position System (GPS) based on a constellation of about 24 satellites orbiting the earth at altitudes of approximately 11,000 miles. In Europe, a satellite navigation system named Galileo was deployed by the European Space Agency based on a 30-satellite constellation, to provide positioning and timing services in 2008. Uncorrected positions determined from GPS satellite signals produce accuracies in the range of 50 to 100 meters. When using a technique called differential correction, users can get positions accurate to within 5 meters or less. GPS is effective and accurate outdoors, but it works very poorly, if at all, indoors and in urban canyon environments, due to its extremely weak signal strength. Moreover, GPS is vulnerable to jamming and other disruptions from manmade and natural causes.
Different new alternative position location systems were recently proposed based on other wireless communication systems, such as cellular phone networks and wireless LAN. However, position systems based on cellular networks can only achieve very limited accuracy with locationing error often large than few hundred meters. Position location system based on wireless LAN is more accurate within the service area of network. However, its application is limited by the network coverage.
In addition, most of the existing position location systems are passive, i.e., without any interaction or tracking capabilities. Also signals from different communication transmitters in existing systems are not synchronized, leading to the lack of timing reference for position location applications. In addition, existing position location system works separately from communication systems, leading to technical difficulty and time delay for user interaction and position tracking. The security of the systems is also a major disadvantage.
Generally the relevant prior art requires the use of a spatial reference in order to enable the location/tracking of a network-connected device. Furthermore, prior art examples generally require that the network component utilized provide a stable spatial reference. To achieve these requirements the prior art often involve significant infrastructure and have high associated costs. Moreover, several prior art solutions provide less than optimal accuracy in connection with the tracking of network-connected devices, as opposed to locationing abilities.
As an example, the relevant prior art includes U.S. Pat. No. 6,674,403 which discloses a system and method for performing real-time position detection and motion tracking of mobile communication devices moving about in a defined space comprised of a plurality of locales. The disclosed invention includes a network, a plurality of detectors and at least one processing system. A digital definition of the physical space is combined with a statistical signal strength model to provide a context within which mobile devices may be detected and tracked. Position detection and motion tracking are accomplished within and among the locales by processing actual signal strength data of a mobile device as it moves about or resides in the defined space, and comparing the actual data against the known statistical strength model.
As a further example, the relevant prior art includes U.S. Pat. No. 7,471,244 that discloses monitor units for television signals that comprise a reference clock; a receiver to receive a wireless television signal that may be transmitted by a television transmitter according to a transmitter clock; and a clock offset unit to determine a clock offset between the reference clock and the transmitter clock based on the wireless television signal.